Objective: To explore the mediating effect of self-efficacy between mindfulness and self-esteem. Methods: In this study, 400 junior school students from a middle school in Jiangxi Province was recruited and complete mindful self scale, general self-efficacy scale and self-esteem scale. Results: The scores of mindfulness, self-efficacy, self-esteem were (63.89±9.12), (22.82±4.83) and (26.14±4.43), respectively. Mindfulness and its four dimensions (self-insight, self-acceptance, self-compassion and non-persistence) were significantly positively correlated with self-esteem (r=0.18-0.53, all P<0.01). Mindfulness and its three dimensions (self-insight, self-compassion and non-persistence) were significantly positively correlated with self-efficacy (r=0.22-0.39, all P<0.01). Self-efficacy and self-esteem were significantly positively correlated (r=0.82, P<0.01). Mindfulness positively predicted self-efficacy (β=0.38, P<0.01), self-efficacy positively predicted self-esteem (β=0.74, P<0.01), and mindfulness positively predicted self-esteem (β=0.25, P<0.01). That was, self-efficacy partially mediated the relationship between mindfulness and self-esteem. The mediating effect value was 0.28, accounting for 52.83% of the total effect. Conclusion Mindfulness not only directly affects adolescents' self-esteem, but also influences adolescents' self-esteem through self-efficacy.